renew and revoke should not remove request files

[TinCanTech]

Request files can be used ad-infinitum to create new certificates, keeping request files in place for future use is far more useful than removing them.

The same is true for key files.

This approach naturally leads into CA renewal: #936 and #941

[TinCanTech]

renew does not move request or key files. OK.
This means that the current request and key files are used for renew.

revoke-renewed does move the OLD request and key files. OK
These files are only moved if they exist.
They do not exist because renew does not move them to the renewed folders.

revoke does move request and key files. OK

This is probably the least complicated method.